I very much doubt they will see a decline in life-spans. People will go to doctors and pay large amounts of money to have crud hoovered out of their bodies to keep them alive a few more years longer. Now people take pills to lower cholesterol, soon they will have pills that stop them getting fat and problably pills that make them enjoy exercise. Basically people will use money to live longer.

Mind you, I'm assuming there won't be a disaster caused by a crazy mass murderer with the right lab equipment.